This application claims priority to an application entitled xe2x80x9cAntenna Apparatus in Mobile Communication Systemxe2x80x9d filed in the Korean Industrial Property Office on Aug. 18, 2000 and assigned Serail No. 2000-47970, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates generally to an antenna apparatus in a CDMA mobile communication system, and in particular, to an antenna apparatus with a reduced number of antennas in a W-CDMA mobile communication system.
2. Description of the Related Art
Antennas are arranged generally in three sectors in a second generation (2G) (CDMA and PCS) mobile communication system.
FIG. 1 illustrates an antenna layout in the 2G mobile communication system.
Referring to FIG. 1, antennas are arranged in three sectors, each sector containing 120xc2x0 and adjacent to two of the sectors. For reception diversity (Rx diversity), two antennas are provided in each sector. One of the two antennas is used for the dual purpose of transmission and reception (TX/RX antenna) and the other is used exclusively for reception (RX antenna). Each transmission antenna transmits a signal in the direction of a corresponding sector and each reception antenna receives a signal directed to the sector. A received signal is input to a reception port of a pre-processor (not shown) connected to the antenna. A transmission signal generated in the communication system is transmitted through a transmission port of the pre-processor and the transmission/reception antenna (TX/RX antenna) in the corresponding sector. The pre-processor usually operates in a duplexing method. In this structure, an antenna is fabricated with an array of dipole resonators to cover both transmission and reception frequencies. Beyond a predetermined bandwidth, however, the functional efficiency of the resonators is markedly decreased.
For example, in a system having a 250 MHz transmission/reception frequency band between 1920 and 2170 MHz such as an IMT2000 system, the antenna currently in use is composed of such resonators resulting in limitations in the reliability of the overall system. In one attempt to solve this problem, the transmission/reception antenna is separated into a transmission antenna and a reception antenna, resulting in the number of antennas per sector increasing to four (two transmission antenna and two reception antenna) in an IMT2000 system supporting transmission/reception diversity as compared to the 2G system.
Use of four antennas per sector for transmission/reception of signals occupy too much space and requires increased antenna height.
It is, therefore, an object of the present invention to provide an antenna apparatus that overcomes the conventional antenna problems.
It is another object of the present invention to provide an antenna apparatus having a reduced number of triangular shaped antennas, each triangular antenna incorporating a transmission antenna unit for transmitting a transmission signal in the direction of a corresponding sector and a reception antenna unit for receiving a signal directed to an adjacent sector in a mobile communication system.
The foregoing and other objects of the present invention are achieved by providing an antenna apparatus in a CDMA mobile communication system. In the antenna apparatus, a pair of pre-processors are assigned to each of n sectors for transmission and reception diversity. Each pre-processor has a transmission port and a reception port to separate a transmission signal from a reception signal. A pair of triangular antennas are assigned to each sector. In each triangular antenna, a transmission antenna unit transmits a transmission signal received via a transmission port in its sector in the direction of the sector, and a reception antenna unit, connected to the transmission antenna unit at a predetermined horizontal angle xcex8, receives a signal directed to an adjacent sector and sends the received signal to the reception port of a pre-processor in the adjacent sector.